Background. The ω-3 PUFA drug is presently proved to decrease mortality of patients with IHD; however, efficacy of this drug has not been studied in patients with multivessel coronary disease after a primary transcutaneous coronary intervention (TCI). Aim. To evaluate effects of the long-term ω-3 PUFA (Omacor, Solvay Pharma) treatment on the course of IHD after a primary TCI for multivessel coronary disease. Materials and methods. The study included 101 patients aged 35 to 70 who have had a primary TCI for ST segment elevation myocardial infarction (STEMI) and multivessel coronary disease. Patients were divided into 2 groups: group 1 (n=68), conservative tactics using a standard drug therapy; group 2, (n=33), standard drug therapy supplemented with ω-3 PUFA. Results. At 36 months, incidences of recurrent MI, decompensated CHF, progressive angina, and heart rhythm disorders were lower in the ω-3 PUFA treatment group. Thus, ventricular extrasystole >3 Lown’s grade was observed in 84.6 % of patients in group 1 and in63.6 % of patients in group 2 (OR, 0.75; 95 % CI, 0.64–0.87; р=0.05); atrial extrasystole was observed in 100 % and 90.9 % of patients, respectively (OR, 0.90; 95 % CI, 0.84–0.96; р=0.05). For the 36‑month observation period, patients of group 2 achieved a better anti-ischemic effect, which was evident as an 80.9 % decrease from baseline in angina rate (р<0.047) and a 27.6 % decrease from baseline in CHF severity. The increase in exercise tolerance by results of the 6‑min walk test was greater in group 2, 65 % (from 166.2 to 323.5 m). Conclusion. Long-term administration of ω-3 PUFA to patients with STEMI associated with multivessel coronary disease after a primary TCI resulted in improvement of their clinical condition, which was evident as increased exercise tolerance and improved quality of life.